title: Trends in serotypes and sequence types among cases of invasive pneumococcal disease in Scotland, 1999-2010.
abstract: BACKGROUND
  The 7-valent pneumococcal conjugate vaccine (Prevenar(®), Wyeth; PCV7) was introduced to the UK paediatric immunisation schedule in 2006. This study investigates trends in serotypes and multi locus sequence types (STs) among cases of invasive pneumococcal disease (IPD) in Scotland prior to, and following, the introduction of PCV7.
  
  
  METHODS
  Scottish Invasive Pneumococcal Disease Enhanced Surveillance has records of all cases of IPD in Scotland since 1999. Cases diagnosed from blood or cerebrospinal fluid isolates until 2010 were analysed. Logistic and poisson regression modelling was used to assess trends prior to and following the introduction of PCV7.
  
  
  RESULTS
  Prior to PCV7 use, on average 650 cases of IPD were reported each year; 12% occurred in those aged <5 years and 35% affected those aged over 65 years. Serotypes in PCV7 represented 47% of cases (68% in <5 year olds). The serotype and ST distribution was relatively stable with only serotype 1 and associated ST 306 showing an increasing trend. PCV7 introduction was associated with a 69% (95% CI: 50%, 80%) reduction in the incidence of IPD among those aged <5 years, a 57% (95% CI: 47%, 66%) reduction among those aged 5-64 years but no significant change among those aged 65 years and over where increases in non-PCV7 serotypes were observed. Serotypes which became more prevalent post-PCV7 are those which were associated with STs related to the PCV7 serotypes.
  
  
  CONCLUSIONS
  Routine serotyping and sequence typing in Scotland allowed the assessment of the relationship between the capsule and the clones in the post vaccination era. Changes in the distribution of serotypes post PCV7 introduction appear to be driven by associations between serotypes and STs prior to PCV7 introduction. This has implications for the possible effects of the introduction of higher valency vaccines and could aid in predicting replacement serotypes in IPD.
authors.affiliation: Department of Mathematics and Statistics, University of Strathclyde, 26 Richmond Street, Glasgow, United Kingdom; Clinical Epidemiology and Biostatistics Unit, Murdoch Children's Research Institute, Royal Children's Hospital, Flemington Road, Parkville, VIC, Australia. Electronic address: karen.lamb@mcri.edu.au.
authors.forename: Karen E
authors.initials: KE
authors.lastname: Lamb
authors.affiliation: Department of Mathematics and Statistics, University of Strathclyde, 26 Richmond Street, Glasgow, United Kingdom; Immunisation, Hepatitis and Blood Safety Department, Health Protection Agency, 61 Colindale Avenue, London, United Kingdom.
authors.forename: Stefan
authors.initials: S
authors.lastname: Flasche
authors.affiliation: Molecular Diagnostics East Midlands Pathology Clinical Microbiology Department, Queens Medical Centre, Nottingham, United Kingdom.
authors.forename: Mathew
authors.initials: M
authors.lastname: Diggle
authors.affiliation: Department of Microbiology, Monklands Hospital, Monkscourt Avenue, Airdrie, United Kingdom.
authors.forename: Donald
authors.initials: D
authors.lastname: Inverarity
authors.affiliation: Department of Mathematics and Statistics, University of Strathclyde, 26 Richmond Street, Glasgow, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Greenhalgh
authors.affiliation: Molecular Microbiology Group, Sir Henry Wellcome Laboratories, Academic Unit of Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom; Southampton NIHR Respiratory Biomedical Research Unit, University Hospital Southampton Foundation NHS Trust, Southampton, United Kingdom.
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Jefferies
authors.affiliation: Infection and Immunity Research Group, Glasgow Dental School, Faculty of Medicine, University of Glasgow, Glasgow, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Smith
authors.affiliation: Scottish Haemophilus, Legionella, Meningococcus and Pneumococcus Reference Laboratory, Stobhill General Hospital, Glasgow, United Kingdom.
authors.forename: Giles F S
authors.initials: GF
authors.lastname: Edwards
authors.affiliation: Scottish Haemophilus, Legionella, Meningococcus and Pneumococcus Reference Laboratory, Stobhill General Hospital, Glasgow, United Kingdom.
authors.forename: Barbara
authors.initials: B
authors.lastname: Denham
authors.affiliation: Health Protection Scotland, Glasgow, United Kingdom.
authors.forename: Jim
authors.initials: J
authors.lastname: McMenamin
authors.affiliation: Health Protection Scotland, Glasgow, United Kingdom.
authors.forename: Eisin
authors.initials: E
authors.lastname: McDonald
authors.affiliation: Institute of Microbiology and Infection, School of Immunity and Infection, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Mitchell
authors.affiliation: Molecular Microbiology Group, Sir Henry Wellcome Laboratories, Academic Unit of Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom; Health Protection Agency, Southampton, United Kingdom; Southampton NIHR Respiratory Biomedical Research Unit, University Hospital Southampton Foundation NHS Trust, Southampton, United Kingdom.
authors.forename: Stuart C
authors.initials: SC
authors.lastname: Clarke
authors.affiliation: Department of Mathematics and Statistics, University of Strathclyde, 26 Richmond Street, Glasgow, United Kingdom; Health Protection Scotland, Glasgow, United Kingdom. Electronic address: chris.robertson@strath.ac.uk.
authors.forename: Chris
authors.initials: C
authors.lastname: Robertson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D016015:Logistic Models; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D011159:Population Surveillance; D012606:Scotland / Q000453:epidemiology; D065288:Serogroup; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification*; D018074:Vaccines, Conjugate / Q000008:administration & dosage; D055815:Young Adult
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate
keywords: Invasive pneumococcal disease; PCV7; Sequence type; Serotype